Prior U.S. Pat. No. 3,921,819 discloses a latching and pin locking mechanism for multi-section telescoping booms which enables the safe operation of the boom fly section without the necessity for extending hydraulic lines and electrical control cables forwardly in the boom structure to the locations of the latch plunger and locking pins or to points near these locations, thus rendering the use of the fly section much more economical and practical.
However, in the noted prior patent, a serious drawback exists in that the latching and pinning mechanism can only be operated when the bottom is in a horizontal, or substantially horizontal, position so that a human operator can have access to controls for the latching plunger and locking pin. This is a serious disadvantage when the crane must be operated in close quarters, such as in an oil refinery where available space is very limited.
Accordingly, it is the major object of this invention to improve significantly on the arrangement in the noted prior patent through provision of a remotely operated hydraulic power system through which the cooperative latching plunger and locking pin means can be conveniently operated regardless of the elevation or angle of the crane boom, therefore greatly expanding the entire range of utility of the crane and the latch and locking pin arrangement which forms the heart of the invention.
Another very important aspect of the invention is the provision within the hydraulic control circuit for the latching plunger and locking pin means of a safety interlock arrangement which renders it impossible for these two components to be operated in improper sequence which otherwise could allow the fly section to be unsupported causing its sudden collapse.
The present invention continues to include the advantage that hydraulic lines and/or electrical lines do not have to be extended forwardly into the fly section of the boom to effect operation of the latching plunger and locking pin from a remote point. Therefore, the basic economies and simplicity achieved in prior U.S. Pat. No. 3,921,819 are retained but without the restriction that the system can only be operated while the boom is in a horizontal position.
Other features and advantages of the invention will become apparent from the specification hereinafter following be reference to the accompanying drawings.